Seal bearing assembly for use in a solid waste comminutor

ABSTRACT

A solid waste material comminuting system having a  an electric motor for providing rotary motion, a pair of cutter stacks with cutter elements of one stack interleaved with cutter elements of the other, and gear means to transmit the rotary motion of the electric motor to counter-rotate cutter elements of one stack with cutter elements of the other. Each of the cutter stacks comprises a central shaft journaled for rotation and a seal-bearing assembly/module at each end of the central shafts. Each bearing  assembly/module comprises an end housing, and a pair of insertable pre-assembled seal-bearing elements/assemblies mountable in each of said end housings. One seal-bearing element/assembly has a thru-hole for journaling a first shaft for rotation and a second seal-bearing element/assembly has a thru-hole for journaling a second shaft for rotation.

This is a continuation of application Ser. No. 08/077,106 filed Jun. 16,1993 now U.S. Pat. No. 5,354,004.

BACKGROUND OF INVENTION

This invention relates to a solid waste comminuting apparatus. Suchdevices have been established in the art and are now widely used in avariety of industrial applications, such as municipal waste treatmentand industrial applications. Reference is made to U.S. Pat. No.4,046,324, which discloses such a basic system that has achievedcommercial success.

By definition, comminution is the reduction of particle size of solidwaste material to minute particles. It is generally performed byshearing, shredding and crushing of the waste material. As set forth inthe '324 patent, comminution occurs by utilizing a pair ofcounter-rotating intermeshed cutting members.

The solid waste material is fed into the interface between cuttingelements, typically utilizing a fluid carrier medium, and shearingaction occurs because the two cutters overlap each other such thatopposing forces of counter-rotation of the cutting elements on thedifferent stacks act on the solid material as it passes through thedevice.

In practice, such devices are generally used in an enfluent path. Thatis, the solid material is generally entrained in a liquid and the deviceis placed directly in the liquid stream. By having the solid materialentrained in a liquid stream transportation of the material to and fromthe unit occurs. Further, by softening the solid particles, a greaterdegree of comminution is achieved. Devices of the type disclosed in the'324 patent have found commercial success and are widely used in wastetreatment facilities, shipboard use and the like. As can be appreciated,the environment of use is very harsh for the equipment and as such,routine maintenance is required in both a preventative sense and also toimmediately repair break downs when they occur thus minimizing systemdown-time.

An important aspect of such maintenance and repair is the integrity ofthe seals which provide the cutter stacks to rotate while minimizingfriction. Given the mass of the cutter stacks together with high motortorque, loads on the seals are large and thus seal integrity is aprimary consideration. In the past, two-shafted machines such as the'324 device required that the seal assembly be an integral part of thedevice. Such is illustrated in FIG. 1 of the '324 patent. As a result,if there was a seal failure other critical components of the device werelikely to be effected. This failure of a seal could thus mean thatbearings could fail and seize up the cutter stack.

Importantly, to repair the seal assembly, in the prior art, there was arequirement that the device be disassembled and completely reassembled.In the context of a unit which is used in fluid waste treatment thatdown-time, in some cases as long as a day could have detrimental effectsin the ability of a plant to process waste. Such would require reroutingsolid waste, shutting down a portion of the facility and otherwiseresult in an inefficient operation.

Moreover, in prior art two-shafted machines, the cutter stack and thevarious seal components were integral and in-line with a fixed geometry.Consequently, tightening of the cutter stack, by compression, resultedin compression of the seals. Again, such is illustrated in FIG. 1 of the'324 patnet. It has been recognized however, that under normal operatingconditions the cutter thickness experiences wear and thus the overallthickness of the stack tends to reduce over time. The result is aneffective reduction in the overall stack height and the stack thereforetends to become loose. As a consequence, initial compression of variousseal components is lost and the seal faces tend to separate. The resultis leakage across the seal with the subsequent result of bearingfailure.

Another deficiency in the prior art was the use of a labyrinth betweenthe main fluid chamber and the seal faces. The labyrinth was generallyincorporated into the seal components as sacrificial component. Becausesuch devices are used in applications which include a high grit content,the labyrinth tended to be a relatively high wear component. As aconsequence, seal components had to be removed to replace the labyrinthwith the potential for seal damage upon reassembly.

SUMMARY OF THE INVENTION

Given these deficiencies in the prior art, it is an object of thisinvention to provide an improved solid waste comminutor that overcomesthe operational and assembly problems of prior devices.

It is a further object of this invention to provide a solid wastecomminutor which employs a cartridge with a balanced seal-bearing designto produce a constant seal face pressure.

A further object of this invention is to provide a solid wastecomminutor of improved seal and bearing life by improved sealeffectiveness which is independent of stack tightness.

Yet another object of this invention is to provide a seal cartridge fora solid waste comminutor which has an independent labyrinth that can bereplaced without disassembly of the seal-bearing structure.

Another object of this invention is to provide an improved solid wastecomminutor that utilizes a separate wear piece independent of the sealcartridge which itself may be pre-loaded to provide a spring force forthe cutter stack.

These and other objects of this invention are achieved by a dual stacksolid waste comminutor having preassembled bearing-sealed elements thatare replaceable individually. That modular assembly improves system lifewhile minimizing down-time. In accordance with this invention acartridge type seal is employed utilizing two modular assemblies, one oneach end of the cutter stack. Each of the modular bearing-sealassemblies comprises a pair of identical bearing-seal cartridges. Twoidentical bearing-seal cartridges are assembled into the end housing tothus form top and bottom modular pairs.

Further, in accordance with this invention the bearing-seal cartridgesfloat within the housing to provide movement with shaft movement therebyreducing the stress on the shafts and bearings.

A quick exchange of the mechanical subassembly, which includes bearings,O-ring seals and cartridge housing itself can be effectuated. As aresult of this modular assembly, an individual seal cartridge can beinstalled quickly without the need to disassemble the entiresubassembly.

Another advantage of this technique is that the bearing-seal cartridgeis identical for the top and bottom of the cutter stack. As aconsequence, a deficiency in the prior art which used two differentassemblies has been eliminated. The bearing-seal cartridge is an itemwhich is pre-assembled and installed as received. Thus, there is norequirement that the individual items, the various races bearings andthe like be assembled at the job site. Rather, the cartridge isinterchangeable as a unit and is inserted into the end housing.

Further, in accordance with this invention by re-torquing of the cutterstack can be accomplished while the unit is still in-line and installed.It has been demonstrated that in practice, the most common preventativemaintenance function is re-torquing the cutter stack to maintain stackcompression for maximum cutting efficiency.

Prior to this invention a loss of stack compressibility lead directly topremature seal and bearing failure, primarily of the bottom sealassembly. In accordance with this invention, the tightness of the sealassembly is independent of total stack height, since it is designed as aself contained unit no disassembly is required.

Another advantage of this invention is an early warning seal failuredetection system which can be used to prevent premature bearing failure.The invention provides for a drain port and/or weep holes in the shaftsthat allow fluid permeating from the seal to escape to the exterior.This can thus be viewed by maintenance personnel during routine checksof the system.

These and other objects of this invention will become apparent by areview of the attached drawing and the description of the preferredembodiment which follows.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cut-away side view of the overall comminution system of thisinvention; and

FIG. 2 is a schematic view illustrating the seal cartridges and theirassembly to form a dual seal cartridge .

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a cut-away side view of the overall system isdepicted. In FIG. 1 the housing 1 has an inlet and outlet, notillustrated. At the bottom of the housing, a pair of access cut-outs 4are provided to permit stack tightening, to be described herein, withoutdisassembly of the device. The unit employs, three essential subsystems,which comprise a complete comminution apparatus 10. These are a drivesubsystem 11 with a motor 24 and speed reducer 12, a gearing subsystem14, and a cutting subsystem 16. The housing 26 for the speed reducer 12is mounted to the gear and cutter system 14, 16 by a pair of conformingflange elements 18, 20, which are clamped together by means of bolts 22.The motor is typically an electric drive motor 24, the details of whichneed not be discussed in detail. It will be recognized by those skilledthat a suitable motor and drive system can be employed consistent withthe scope of intended use. The speed reducer is contained in a housing26 and employs an input shaft 30 and an output shaft 28. The input shaft30 is journaled for rotation using a coupling 32 to the motor 24. Thisprovides axial and radial alignment of the motor unit 24 with the speedreducer 12.

The output shaft 28 of the speed reducer 12 passes through a transitionpiece 34 in which the output shaft 28 is keyed to a drive shaft 36 ofone cutter stack by means of a coupling 35. The drive shaft 36 carries agear 38. The drive shaft 37 of the other cutter stack carries a gear 40.Both gears 38 and 40 are housed in housing 42 of the gear unit 14. Thetwo gears provide counter-rotation to a pair of cutter stacks 44, 46.That is, shaft 36 is the drive shaft and shaft 37 is the driven shaftwhich counter-rotates due to gears 38, 40.

Each of the cutter stacks 44, 46 comprises an alternating sequence ofcutting elements 48 and spacers 50. As illustrated in FIG. 1, theinterface is such that by beginning the stack 44 with a cutter elementand stack 46 with a spacer element the cutter elements interleave witheach other in the area between the two cutter stacks, which has beendenoted by numeral 52. It is this interactive pair of stacks in zone 52which provides the shredding of material as it passes through the cutterelements.

The cutter elements themselves may be either the same on each stack ordiffer from stack to stack. For example, it has been found that havingeleven teeth on one cutter element and five on the opposing elementimproves the clean-out efficiency of the unit. Moreover, the geometry ofthe cutter elements may also be different in addition to the variationsin the number of teeth.

As illustrated in FIG. 1, the cutter stack 16 is supported top andbottom by means of a pair of bearing-seal assemblies/modules 54, 56.FIG. 2 illustrated in greater detail those two subassemblies.

Referring now to FIG. 2, the assemblies/modules 54 and 56 are explainedin greater detail. It will be understood from reference to FIG. 1 thatthe assembly on top 54 is the same as the assembly on the bottom 56, theunit simply being inverted. FIG. 2 illustrates the seal bearing assembly56. The units are assembled into respective end housings, 58 and 60.FIG. 2 illustrates the end housing 60. As illustrated, two identicalbearing-seal cartridges are employed in the end housing. FIG. 2illustrates on seal one element/assembly 62 in place with a second sealelement/assembly 64 being inserted into the end housing 60.

Illustrated in phantom line in FIG. 2 are the ends 66, 68 of the shafts36 and 37 for the respective cutter assemblies 44 and 46. It will beunderstood that the shaft ends 66 and 68 protrude through the respectiveseal cartridges but are held in place by end nuts 69. Stack tightness isachieved by tightening the end nuts 69. Access is via the cut-outs 4 sothat an individual stack may be tightened. O-rings 70, and 72 areemployed to provide a fluid tight seal for each shaft.

As illustrated in FIG. 2, the bearing-seal cartridge comprises acartridge housing 74 with an outer flange 76 and an inner tubularportion 78. A spring 80 is inserted between the flange portion 76 andthe cylindrical portion 78. A dynamic race 82 sealed by means of anO-ring 84 is placed relative to the spring 80 and the cylindricalportion 78. This spring provides a means by which the race 82 isprovided with float.

A static race 86 with an O-ring 84 forms the dual race structure. Therace is held in place by means of the bearing cartridge 88 having aflange element 91 to cage the static race into position and to alsolimit axial travel of the dynamic race. The dynamic race 82 has a facein contact with a confronting face of static race 86. A bearingstructure 90 is housed inside the bearing cartridge and is held in placeby means of a retaining ring, such as a snap ring illustrated as element92.

A second spring 87 may optionally be used to allow the races 82 and 86to axially float. The advantage is prevention of potential skew of thefaces of the races relative to each other.

As illustrated in FIG. 2, the second seal cartridge element/assembly hasan identical construction of its elements. The units are held in placeand are biased by means of springs 94, 96. Those springs provide floatfor the bearing-seal cartridges 62, 64, 66 .

Sealing occurs by means of O-rings 98, 100. It will be appreciated thatwith respect to the seal cartridge illustrated in its installed positionon the right hand side of FIG. 2 the same elements are present. Theyhave been denoted with prime numbers to connote the same numberingsequence.

While not illustrated, it is apparent from FIG. 1 that the upper endhousing, inverted having a pair of identical seal cartridges isemployed. The upper end seal-bearing module may be provided with anupper spacer 103. This spacer rests on the outer race to preload the topbearing stack as the housing 42 is mounted on the housing 58 via bolts104.

Importantly, in accordance with this invention the labyrinth illustratedby dotted lines with numeral 102 is not a part of the seal-bearingassembly. Rather, the labyrinth is considered to be a part of the stackassembly and is separated from the seal cartridge assembly itself. Thelabyrinth 102 protrudes to the enfluent effluent stream where it issubjected to particles and the like while the device is in operation.Hence, it is a component that wears and must, from time to time bereplaced. In accordance with this invention, the labyrinth 102 can bereplaced as a single component since it is merely placed into theannular groove 108 of the housing 60. It is compressed into position bya force applied through annular raised surface 110 that loads thelabyrinth on surface 111, and causes it to slightly deflect. Thisdeflection serves to compensate for wear in the cutter stack.

As is apparent from FIGS. 1 and 2, this construction offers a number ofimportant advantages. First, given the fact that the seal-bearing-sealassemblies are a include modular cartridge assembly cartridges, repairof a seal assembly requires only that a pre-assembled cartridge 64 beinstalled in place of the defective unit. Thus, the seal and bearingcomponents and the bearing elements are combined into a single cartridgeassembly 64. This allows for important advantages over the prior art inthat the individual components do not have to be disassembled at a jobsite.

Secondly, by this invention stack tightening occurs independent ofcompression forces on the seal components. This occurs because, inaccordance with this invention, the cartridges themselves are positionedand loaded independent of the cutter stack. That is the housing 58 isattached to gear housing 42 by means of the bolts 104. Tightening thecutter stacks by means of the nuts 69 does not increase the forces onthe bearings or seals. Rather, the force is a function of the springforce of the spring 80.

In the case of the upper assembly, axial positioning is obtained by thespacer 103 which opposed by spring 94 as the unit is bolted by means ofbolts 104. The bottom assembly is allowed to float. The bottom assemblyis mounted by means the mounting bolts 106. The use of a spacer iseliminated. It is understood that the cover plates and mountingstructure of the housing 1 have been eliminated.

This invention also includes a provision of leak detection by means of aleak detection plug 108. Thus, an upper seal failure can be ascertainedby fluid in the upper housing via the leak detection plug 108. If thereis any water in the warea, it will alert personnel that there is apotential failure in the upper bearing-seal.

Additionally, a leakage path can be provided in each of the shafts 36,37. To the extent that fluid permeates the seal it will thus escape tothe exterior where it can be viewed during routine maintenance checks.

As set forth in this invention, in accordance with this invention acartridge type bearing-seal 64 allows for replacement of units on anindividual basis as opposed to replacement of the entire seal pair atthe top or bottom of the cutter stack. Additionally, the entire assemblywith the bearings intact can be removed from the housing for servicing.Given the construction of those cartridge elements tightening of thecutter stack can be accomplished without impairing the effectiveness ofthe seal. That is, compression of the seal components themselves occursduring the assembly of each of the seals cartridge units illustrated inFIG. 2. Thus, the integrity of those units is accomplished independentof the tightness of the cutter stack.

Moreover, as illustrated in FIGS. 1 and 2 the labyrinth 102 is placedbetween the main fluid chamber and either of the seal faces. In thisinvention the labyrinth 102 is distinct and separate from each of theseal cartridges. To the extent that the labyrinth requires replacement,it can be done by removing the cartridge, inserting a new labyrinth andthen reinstallation of the cartridge 56, 60 without any disassembly ofthe seal components.

It will be apparent to those of skill in this technology thatmodifications of this invention can be made without departing from theessential scope thereof.

1. A seal bearing assembly for use in a comminuting solid waste materialdevice having a pair of cutting stacks with cutter elements of one stackinterleaved with cutter elements of the other, drive means to producecounter-rotation of cutter elements of one stack with cutter elements ofthe other, each of said cutter stacks comprising a central shaftjournaled for rotation proximate each end; said seal-bearing assemblycomprising; an end housing, a pair of insertable preassembledseal-bearing elements mountable in said end housing, one seal-bearingelement having a thru-hole for journaling a first shaft for rotation anda second seal-bearing element having a thru-hole for journaling a secondshaft for rotation and a seal for each of said first and secondseal-bearing elements to provide fluid isolation between said endhousing and said first and second seal-bearing elements.
 2. The bearingassembly of claim 1, wherein said preassembled seal-bearing elementscomprises comprise a seal cartridge, a spring mounted on the sealcartridge, a dynamic race biased by said spring, a bearing cartridge, astatic race mounted on said bearing cartridge, a bearing of saidseal-bearing element being mounted in said bearing cartridge and meansto secure said bearing in said bearing element cartridge and to urgesaid static race into contact with said dynamic race.
 3. The bearingassembly of claim 2 further comprising wherein a seal of saidseal-bearing element comprises means to fluid fluidly isolate saidbearing from said static race.
 4. The bearing assembly of claim 2further comprising spring means to bias said bearing cartridge in saidend housing.
 5. The bearing assembly of claim 2, wherein saidpreassembled seal-bearing elements further comprising comprise a springto bias said static race and provide axial float for said static anddynamic races.
 6. The bearing assembly of claim 1 further comprising alabyrinth positioned on top of both seal-bearing elements, saidlabyrinth insertable onto said end housing and having a flangeconforming in shape to a portion of said end assembly proximate to saidcutter stacks.
 7. The bearing assembly of claim 1 further comprising alabyrinth mountable on said end housing and protruding in part into anenfluent effluent stream, said labyrinth having a bearing surface thatcauses said labyrinth to elastically deform and compensate for variationsin variations in cutter stack height.
 8. A seal-bearing module for usein a solid waste material comminuting system having a pair of cutterstacks with cutter elements of one stack interleaved with cutterelements of the other, an electric motor to counter-rotate cutterelements of one stack with cutter elements of the other, saidseal-bearing module comprising; an end housing, and a pair of insertablepre-assembled seal-bearing assemblies mountable in said end housing, oneseal-bearing assembly having a thru-hole for journaling a first shaftfor rotation and a second seal-bearing assembly having a thru-hole forjournaling a second shaft for rotation and a seal for each of saidseal-bearing assemblies to isolate each of the seal-bearing assembliesfrom said end housing.
 9. The seal-bearing module of claim 8, whereinsaid preassembled seal-bearing assemblies comprises comprise a sealsseal cartridge, a spring mounted on the seal cartridge, a dynamic raterace biased by said spring, a bearing cartridge, a static race mountedon said bearing cartridge, a bearing of said seal-bearing assembly beingmounted in on said bearing cartridge and means to secure said bearing insaid bearing assembly cartridge.
 10. The seal-bearing module of claim 9further comprising wherein a seal of said seal-bearing assemblycomprises means to fluid fluidly isolate said bearing from said staticrace.
 11. The seal-bearing module of claim 9 further comprising springmeans to bias said bearing cartridge in said end housing.
 12. Theseal-bearing module of claim 9, wherein said preassembled seal-bearingassemblies further comprising comprise a spring to bias said static raceand provide axial float for said static and dynamic races.
 13. Theseal-bearing module of claim 8 further comprising a labyrinth positionedon top of said seal-bearing module to provide a wear interface betweensaid seal-bearing module and an enfluent effluent flow, said labyrinthconforming to a portion of said end assembly to provide a removablemounting surface.
 14. The assembly of claim 1, wherein saidpre-assembled seal-bearing elements each include a bearing housing and aseal housing.
 15. The assembly of claim 14, wherein said bearing housingis configured to receive a bearing structure of said pre-assembledseal-bearing element.
 16. The assembly of claim 15, wherein said bearingstructure is fixedly retained in said bearing housing.
 17. The assemblyof claim 1, wherein said pre-assembled seal-bearing elements eachinclude a seal housing.
 18. The assembly of claim 17, further comprisinga dynamic race and a static race, wherein said dynamic race and saidstatic race are retained by a flange of said seal housing.
 19. Theassembly of claim 17, wherein each of said seal housings defines athru-hole for journaling said first and second shafts respectively. 20.The module of claim 8, wherein said pre-assembled seal-bearingassemblies each include a bearing housing and a seal housing.
 21. Themodule of claim 20, wherein said bearing housing is configured toreceive a bearing structure of said pre-assembled seal-bearing assembly.22. The module of claim 21, wherein said bearing structure is fixedlyretained in said bearing housing.
 23. The module of claim 8, whereinsaid pre-assembled seal-bearing assemblies each include a seal housing.24. The module of claim 23, further comprising a dynamic race and astatic race, wherein said dynamic and static races are retained by aflange of said seal housing.
 25. The module of claim 23, wherein each ofsaid seal housings defines a thru-hole for journaling said first andsecond shafts respectively.
 26. A seal bearing assembly for use in acomminuting solid waste material device having a pair of cutting stackswith cutter elements of one stack interleaved with cutter elements ofthe other, drive means to produce counter-rotation of cutter elements ofone stack with cutter elements of the other, each of said cutter stackscomprising a central shaft journaled for rotation proximate each end;said seal-bearing assembly comprising; an end housing, a pair ofinsertable preassembled seal-bearing elements mountable in said endhousing, one seal-bearing element having a thru-hole for journaling afirst shaft for rotation and a second seal-bearing element having athru-hole for journaling a second shaft for rotation and a seal for eachof said first and second seal-bearing elements to provide fluidisolation between said end housing and said first and secondseal-bearing elements, said insertable preassembled bearing elementseach comprising a bearing housing and seal housing.
 27. The assembly ofclaim 26, wherein said bearing housing is configured to receive abearing structure of said pre-assembled seal-bearing element.
 28. Theassembly of claim 27, wherein said bearing structure is fixedly retainedin said bearing housing.
 29. The assembly of claim 26, furthercomprising a dynamic race and a static race, wherein said dynamic andstatic races are retained by a flange of said seal housing.
 30. Theassembly of claim 26, wherein each of said seal housings defines athru-hole for journaling said first and second shafts respectively. 31.A seal-bearing module for use in a solid waste material comminutingsystem having a pair of cutter stacks with cutter elements of one stackinterleaved with cutter elements of the other, an electric motor tocounter-rotate cutter elements of one stack with cutter elements of theother, said seal-bearing module comprising; an end housing, and a pairof insertable pre-assembled seal-bearing assemblies mountable in saidend housing, one seal-bearing assembly having a thru-hole for journalinga first shaft for rotation and a second seal-bearing assembly having athru-hole for journaling a second shaft for rotation and a seal for eachof said seal-bearing assemblies to isolate each of the bearingassemblies from said end housing, said insertable preassembled bearingassemblies each comprising a seal-bearing housing and seal housing. 32.The module of claim 31, wherein said bearing housing is configured toreceive a bearing structure of said pre-assembled seal-bearingassemblies.
 33. The module of claim 32, wherein said bearing structureis fixedly retained in said bearing housing.
 34. The module of claim 31,further comprising a dynamic race and a static race, wherein saiddynamic and static races are retained by a flange of said seal housing.35. The module of claim 31, wherein each of said seal housings defines athru-hole for journaling said first and second shafts respectively.